Individual specialization in resource use by a far-ranging marine predator: incidence and implications
Lead Research Organisation:
University of Leeds
Department Name: Inst of Integrative & Comparative Biolog
Abstract
Treating all individuals within a population as ecologically equivalent is an oversimplification and ignoring variation among individuals, particularly with respect to resource use, is likely to impede our ability to grasp a suite of ecological and evolutionary processes. Individual specialization in diet and foraging behaviour has important implications for ecology, evolution (including speciation) and conservation but remains largely unevaluated and poorly understood for most free-living consumers, particularly those that forage over long distances. Some of the longest foraging ranges are found among marine predators where, for instance, pelagic seabirds routinely travel tens to hundreds of kilometres from the breeding site on a single trip. Marine predators are currently facing an unprecedented rate of environmental change as a result of rapid climate-driven changes at lower trophic levels combined with direct effects of industrial and commercial fisheries on prey species. In addition, commercial fisheries currently provide huge quantities of food for some species in the form of bait, undersized catch and offal. Responses of different species to these changes in food availability have been well documented at population level but such data typically mask substantial unexplained variation in responses of individuals. Here we propose to examine the incidence and implications of individual variation in resource use by northern gannets as a model far-ranging marine predator that feeds extensively on both fishery discards and pelagic fish. Resource availability to individuals is often strongly affected by competition with other population members, yet surprisingly little attempt has been made to date to place the responses of marine predators to environmental change within the broader context of density-dependent patterns of resource use. Understanding the nature of individual specializations also has important conservation implications for predicting the response and likely consequences of fisheries and climate related change for apex marine predators. Accordingly in this project, we shall: (i) relate dietary specialization of gannets to individual variation in foraging locations, prey search patterns and capture techniques; (ii) examine the extent of density-dependence of both population-level dietary breadth and individual specialization in diet and foraging behaviour, and; (iii) determine the consequences of individual specialization for different components of reproductive fitness. In addition to answering fundamental questions concerning the generation and maintenance of individual specializations within populations of generalist predators, we shall provide vital information on the foraging ranges and core foraging areas of birds at different colonies. These data will be of great value to conservationists and policy makers concerned with the identification of Important Bird Areas and the establishment of Marine Protected Areas in European waters. We shall also provide information in unprecedented detail on the incidence and consequences of reliance on fisheries discards at different colonies as well as the importance of small shoaling fish (e.g. sandeels). This information is essential to make accurate predictions of population-level impacts of proposed changes to fishery discarding practices in Europe and climate related impacts on the availability of naturally occurring forage fish.
People |
ORCID iD |
Keith Hamer (Principal Investigator) |
Publications
Wakefield ED
(2015)
Long-term individual foraging site fidelity--why some gannets don't change their spots.
in Ecology
Wakefield ED
(2013)
Space partitioning without territoriality in gannets.
in Science (New York, N.Y.)
Votier SC
(2017)
Effects of age and reproductive status on individual foraging site fidelity in a long-lived marine predator.
in Proceedings. Biological sciences
Votier S
(2013)
A Bird's Eye View of Discard Reforms: Bird-Borne Cameras Reveal Seabird/Fishery Interactions
in PLoS ONE
Stauss C
(2012)
Sex-specific foraging behaviour in northern gannets Morus bassanus: incidence and implications
in Marine Ecology Progress Series
Scales KL
(2014)
Mesoscale fronts as foraging habitats: composite front mapping reveals oceanographic drivers of habitat use for a pelagic seabird.
in Journal of the Royal Society, Interface
Grecian W
(2012)
A novel projection technique to identify important at-sea areas for seabird conservation: An example using Northern gannets breeding in the North East Atlantic
in Biological Conservation
Description | 1. Northern gannets, satellite-tracked from 12 neighboring colonies, forage in largely mutually exclusive areas. These colony-specific home ranges are determined by density-dependent competition and may be enhanced by individual-level public information transfer, leading to cultural evolution and divergence among colonies. 2. Within colonies, birds showed marked between-individual differences in searching behaviour along environmental gradients, suggesting that widespread individual foraging consistency may represent specialisation linked with individual responses to environmental conditions. 3. Birds showed high levels of individual foraging site fidelity (IFSF) over three consecutive breeding seasons. However, this was not attributable to individual dietary, behavioural or habitat specialisation. Moreover, our results were not consistent with birds using a purely win-stay, loose-shift foraging strategy. Rather we hypothesise that IFSF is mediated by a tendency for site familiarity, accrued early in life, to canalise subsequent foraging decisions. Our results support the recent iconoclastic hypothesis that seabirds in temperate regions exploit predictable food resources. In addition, our results highlight the need to investigate the effects of early life-history experience on foraging behaviour and individual specialisation, supporting the emerging view that conventional habitat selection models are unrealistic in treating individuals as ecologically equivalent and unbiased by past experience. |
Exploitation Route | These findings have important implications for understanding, predicting and managing responses to key environmental drivers including offshore windfarms, fisheries discards and marine protection areas |
Sectors | Education,Energy,Environment |
Description | Findings contributed to case for NERC Knowledge Exchange Impact Accelerator Grant, awarded 2013, with subsequent report to Department of Energy and Climate Change |
First Year Of Impact | 2013 |
Sector | Energy,Environment |
Impact Types | Cultural |
Description | Knowledge Exchange Impact Accelerator Grant |
Amount | £24,263 (GBP) |
Organisation | Natural Environment Research Council |
Sector | Public |
Country | United Kingdom |
Start | 10/2013 |
End | 03/2014 |
Title | gannet tracking database |
Description | High-resolution foraging data for individual birds from multiple breeding populations in the UK and Ireland |
Type Of Material | Database/Collection of data |
Year Produced | 2013 |
Provided To Others? | Yes |
Impact | None as yet |
URL | http://www.seabirdtracking.org/ |
Description | Public lecture |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Public/other audiences |
Results and Impact | Talk entitled 'The remarkable foraging behaviour of northern gannets: a tale of flexibility, consistency and constraint' at the Scottish Seabird Centre, 12th May 2011 Excellent audience feedback indicating increased interest and awareness of seabird conservation issues |
Year(s) Of Engagement Activity | 2011 |
Description | TV broadcast |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Public/other audiences |
Results and Impact | Item for Dick and Dom Go Wild, broadcast on CBBC on 27th February 2012 Increase interest and awareness among schoolchildren |
Year(s) Of Engagement Activity | 2012 |
Description | TV broadcast |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Public/other audiences |
Results and Impact | Contribution to Britain's Secret Seas, broadcast on BBC2 on 9th May 2011 Increased public awareness and interest |
Year(s) Of Engagement Activity | 2011 |